SERPINC1 and hereditary antithrombin deficiency: We speculated that the sequence analysis of potential regulatory regions of SERPINC1 in patients with antithrombin deficiency not explained by gene defects affecting exons and flanking regions might identify new regulatory elements and pathways.This strategy identified 3 gene defects disturbing two VDREs of SERPINC1, all with mild consequences on the levels of antithrombin in plasma.